package algorithm_primary.studyMySelf.一二八LongestContinuouSequence;

import java.util.*;

/**
 * @author 衡孟浩
 * @date 2023/8/11 13:27
 * <p>
 * 给定一个未排序的整数数组 nums ，找出数字连续的最长序列（不要求序列元素在原数组中连续）的长度。
 * <p>
 * 请你设计并实现时间复杂度为 O(n) 的算法解决此问题。
 * <p>
 * <p>
 * <p>
 * 示例 1：
 * <p>
 * 输入：nums = [100,4,200,1,3,2]
 * 输出：4
 * 解释：最长数字连续序列是 [1, 2, 3, 4]。它的长度为 4。
 * 示例 2：
 * <p>
 * 输入：nums = [0,3,7,2,5,8,4,6,0,1]
 * 输出：9
 * <p>
 * <p>
 * 提示：
 * <p>
 * 0 <= nums.length <= 105
 * -109 <= nums[i] <= 109
 */
public class TestMain {
    public static void main(String[] args) {
        int [] nums = {};
        System.out.println(longestConsecutive(nums));
    }

    /**
     * mySelf
     *
     * @param nums
     * @return
     */
    public static int longestConsecutive(int[] nums) {
        if (nums.length == 0){
            return 0;
        }
        Set<Integer> setNums = new TreeSet<>(Comparator.comparingInt(o -> o));
        for (int num : nums) {
            setNums.add(num);
        }
        int maxCount = 1;
        int currentCount = 0;
        int preNum = setNums.iterator().next();
        for (Integer current : setNums) {
            if (preNum + 1== current) {
                currentCount++;
            } else {
                currentCount = 1;
            }
            preNum = current;
            maxCount = Math.max(maxCount, currentCount);
        }
        return maxCount;
    }


    /**
     * leetCode
     */
    /*public static int longestConsecutive(int[] nums) {
        Set<Integer> num_set = new HashSet<Integer>();
        for (int num : nums) {
            num_set.add(num);
        }

        int longestStreak = 0;

        for (int num : num_set) {
            if (!num_set.contains(num - 1)) {
                int currentNum = num;
                int currentStreak = 1;

                while (num_set.contains(currentNum + 1)) {
                    currentNum += 1;
                    currentStreak += 1;
                }

                longestStreak = Math.max(longestStreak, currentStreak);
            }
        }

        return longestStreak;
    }*/
}
